when the poll is closed, a popup notifier for "signatures and submit"

[nancy919]

When the poll is closed, a notification pops up for "signature and submit"
there are two bottoms: enter this dao homepage after the poll is closed
signatures and submit: return to the voting page

https://www.figma.com/file/pk8LWsByXxfJwPK5VmCeyW/icpdao-update?node-id=0%3A1